For many multimedia applications, not only is processor speed important, but also input/output bandwidth is a critical factor that limits applications on personal computers. To address this limitation, the IEEE 1394 standard enables high-performance multimedia connections with camcorders, televisions, stereos, CD changers, set-top boxes, mixing consoles and music keyboards, as well as traditional personal computer devices. Also known as the "FireWire" standard, IEEE 1394 provides a bus interface standard for portable and desktop computing environments. The IEEE 1394 Standard serves as an important linking technology that bridges the consumer and computer markets and describes a serial bus driven by an advanced communication protocol. The IEEE 1394 serial bus is designed for low system cost, while providing the data transfer rates needed for high-performance peripheral buses.
Developed by the Institute of Electrical and Electronics Engineers (IEEE) and its list of member computer companies, the IEEE 1394 standard is a serial bus interface that enables low-cost, high-speed digital data transfer and communication. Transfer speeds between devices can reach up to 400 megabits per second (mbps) via both asynchronous and isochronous data transfer modes. The IEEE 1394 Standard interface lends itself to video applications because it operates an isochronous time-slice system. For example, if the system was configured to output one frame per 1/15 seconds, at least one frame will exist in every packet that is sent out. This results in smooth looking video. For that reason, the IEEE 1394 Standard interface is highly compatible with technologies like asynchronous transfer mode (ATM) which also operates in an isochronous mode.
Benefits of the IEEE 1394 Standard are a real-time transmission of data that provides the benefit of an ideal interconnect for multimedia applications. Using a small, durable and flexible cable and cable connectors, the IEEE 1394 Standard generates cost savings and eliminates certain cable requirements. The IEEE 1394 Standard provides universal input/output interconnects that integrate input/output ports while consolidating printed circuit board space. Moreover, the IEEE 1394 Standard provides peer-to-peer communication structure that permits peripherals to communicate directly with each other without burdening the host unit.
The IEEE 1394 Standard provides a high speed serial bus that uses packetized data that includes a header. The header includes routing information. In addition, the packetized data includes payload data. Physical characteristics of the media are not necessarily designed for a long transmission distance. The IEEE 1394 Standard is designed for short distances such as local area networks that operate on a desktop bus. The distances are often longer than simply the desktop, but the IEEE 1394 Standard is not intended to be used for local area network operations. In essence, therefore, the IEEE 1394 Standard provides a high speed interconnect to replace serial buses and parallel buses for accessing devices such as workstations, home computers, televisions, VCRs, and camcorders with various media types such as audio, video and text.
A limitation associated with existing interface devices is that there is no effective way to provide an automatic path for receiving video packets from many types of desktop cameras, such as certain Sony desktop cameras and sending payload video data to a display interface bus. One way to direct video data into a PC from an IEEE 1394 Standard bus is to feed zoom or video data into the port that allows a the zoom video data input into the associated computer. Currently known video chipsets have the ability to manage in hardware a window that comes in from the zoom port. This permits autonomously displaying the video image in a hardware-managed window, without software operational support.
A significant limitation associated with existing methods for extracting control information relates to data formats. For example, certain Sony cameras provide YUV data, which is real-time data, for transfer across an IEEE 1394 Standard bus. A limitation associated with this raw data is that it comes in an unusual format that does not accommodate the use of other formats from other cameras.
Another problem associated with extracting control information from packetized data is that, because the IEEE 1394 Standard is a relatively new PCI-interface standard available or readily available systems do not all comply with the IEEE 1394 Standard in precisely the same way. This limitation can make some systems, while they comply with the IEEE 1394 Standard, not necessarily be easily compatible with one another.
Yet another important limitation associated with the control and use packetized data transfer according to the IEEE 1394 Standard or similar standards relates to stripping away from the data packets horizontal and vertical synchronous headers. With existing IEEE 1394 Standard bus and associated PCI-Serial Bus interface devices, there is no effective and rapid mechanism for stripping horizontal and vertical synchronous signals that control the display and properly use the associated video image data.